Chapter 13: Sound Section 1 (Sounds Waves) Vocab: Compressions: areas of high pressure Rarefactions: areas of low pressure Pitch: the frequency a sounds wave is percieved to have Infrasonic: frequencies below 20 Hz Ultrasonic: frequencies above 20,000 Hz Doppler Efect: sound source and the detector are moving relative to one another
Humans can hear sounds from about 20 Hz to 20,000 Hz
Speed of sound is approximately 343 m/s
v= speed
f' = pitch
f= frequency Section 2 (Sound Intensity and Resonance)
Vocab: Intensity: the rate at which energy is transferred from one molecule to the next Perceived intensity: dependent on the logarithm of the intensity and is measured in decibels. Resonance: response at certain frequencies Resonant frequency: the amplitude of its vibrations
Threshold of hearing:
Threshold of pain:
Intensity: is the intensity of the sound being measured.
An increase of 10 decibels will be perceived as being twice as loud, and intensity will be increased by a factor of 10 Section 3 (Standing Waves) Vocab:
The lowest frequency able to form a standing wave
Harmonics: frequencies above the lowest frequency Harmonic series: the frequency of each harmonic frequency is equal to the fundamental frequency multiplied by the harmonic number (n) Timbre: sound quality of the resulting sound Beat: two sources that admit sound waves close to each other but are not exactly the same
Fun review problems that YOU SHOULD TRY:
(Section 1)
1. A ambulance passes a stationary listener at 25 m/s. If the frequency of the ambulance's siren is 530 Hz what frequency will the listener hear s the ambulance is approaching and moving away?
(Section 2):
1. If the intensity of a person's voice is 4.6x10 -7 W/m2 at a distance of 2.0 m, how much sound power does this person generate?
2. The power output of a piccolo is 0.35 W. At what distance is the sound intensity of the piccolo 1.2 x 10 -3 W/m2?
(Section 3)
1. What is the fundamental frequency of a .20 m long wine bottle that is closed at one end, when the speed of sound in the pipe is 352 m/s?
2. Mr. Strong uses a 392 Hz tuning fork (when at his side job as a piano tuner) to tune the wire for G natural hears 4 beats per second. What are the two possible frequencies of vibration of this piano wire?
Faughn, Jerry S., and Raymond A. Serway. Physics. Austin: Harcourt Classroom Education Company, 2002.
Section 1 (Sounds Waves)
Vocab:
Compressions: areas of high pressure
Rarefactions: areas of low pressure
Pitch: the frequency a sounds wave is percieved to have
Infrasonic: frequencies below 20 Hz
Ultrasonic: frequencies above 20,000 Hz
Doppler Efect: sound source and the detector are moving relative to one another
Humans can hear sounds from about 20 Hz to 20,000 Hz
Speed of sound is approximately 343 m/s
v= speed
f' = pitch
f= frequency
Section 2 (Sound Intensity and Resonance)
Vocab:
Intensity: the rate at which energy is transferred from one molecule to the next
Perceived intensity: dependent on the logarithm of the intensity and is measured in decibels.
Resonance: response at certain frequencies
Resonant frequency: the amplitude of its vibrations
Threshold of hearing:
Threshold of pain:
Intensity: is the intensity of the sound being measured.
An increase of 10 decibels will be perceived as being twice as loud, and intensity will be increased by a factor of 10
Section 3 (Standing Waves)
Vocab:
The lowest frequency able to form a standing wave
Harmonics: frequencies above the lowest frequency
Harmonic series: the frequency of each harmonic frequency is equal to the fundamental frequency multiplied by the harmonic number (n)
Timbre: sound quality of the resulting sound
Beat: two sources that admit sound waves close to each other but are not exactly the same
Fun review problems that YOU SHOULD TRY:
(Section 1)
1. A ambulance passes a stationary listener at 25 m/s. If the frequency of the ambulance's siren is 530 Hz what frequency will the listener hear s the ambulance is approaching and moving away?
(Section 2):
1. If the intensity of a person's voice is 4.6x10 -7 W/m2 at a distance of 2.0 m, how much sound power does this person generate?
2. The power output of a piccolo is 0.35 W. At what distance is the sound intensity of the piccolo 1.2 x 10 -3 W/m2?
(Section 3)
1. What is the fundamental frequency of a .20 m long wine bottle that is closed at one end, when the speed of sound in the pipe is 352 m/s?
2. Mr. Strong uses a 392 Hz tuning fork (when at his side job as a piano tuner) to tune the wire for G natural hears 4 beats per second. What are the two possible frequencies of vibration of this piano wire?
Faughn, Jerry S., and Raymond A. Serway. Physics. Austin: Harcourt Classroom Education Company, 2002.